An inherently conducting polymer (ICP) began to attract attention since the late 1970s, and the interest in the ICP reached its climax in 1990s. In 2000, the ICP was spotlighted once again as the three (3) scientists, Heeger, MacDiarmid and Shirakawa, received the Nobel award for chemistry. Over recent years, researches on the ICP have been explosively increased. An ICP composite, which is commonly called an organic metal, has been developed or utilized for various uses such as an antistatic agent, various types of organic electrodes, an embedded capacitor or resistor, OLED, or an electroactive material like a solar cell as an organic semiconductor and a corrosion inhibitor. This conductive polymer is a conjugated polymer like a polyacetylene, a polyaniline, a polypyrrole, or a polythiophene, of which a main chain contains a carbon-carbon or carbon-nitrogen double bond, and thus, which is not easily dissolved and lacks stability in the air, and further, exhibits a high brittleness property often, thereby, making the commercialization thereof difficult. In order to overcome the problems, a tremendous number of inventions have been made, and various researches regarding a substance blending approach to blend ICP and an insulting polymer have been conducted over past 30 years [U.S. Pat. No. 5,290,483, U.S. Pat. No. 5,470,505, U.S. Pat. No. 5,520,852, U.S. Pat. No. 5,882,566, U.S. Pat. No. 5,716,550, U.S. Pat. No. 6,168,732, U.S. Pat. No. 5,908,898, U.S. Pat. No. 6,752,935, U.S. Pat. No. 7,683,124, U.S. Provisional Application No. 60/435,256, US2009/0314995A1].
The insulting polymer means any polymers having electrical conductivity of 10−11 S/cm or less other than the ICP, and there has been the attempt to blend a thermoplastic or thermosetting insulating polymer and the ICP to prepare a conductive polymer blend for improvement of processability and physical properties. However, since there is no compatibility between the polymers, most blends do not contribute to the improvement of the electrical conductivity and the mechanical properties, which are essential performances, in addition to the processability. In order to improve the compatibility, methods for improving dispersity have been published as follows: (a) separately adding a deaggregating agent like an ionic or non-ionic plasticizer and a metal salt; (b) blending a polymer-type dopant obtained by modifying an insulating polymer; (c) designing, preparing and using relatively bulky functional organic acid to utilize a dopant itself as a processing aid or a surfactant; (d) providing various steps for a dispersing method to enable fine dispersion like nano-dispersion even though is no compatability; or (e) polymerizing an insulating polymer in the solution state and the ICP and simultaneously blending them in a polymerization process. However, any type of an additive having a low molecular weight cannot improve the properties of the conductive composite having strong brittleness and forming a interionic salt, and when a polymer having a high molecular weight or a polymer-type dopant [Afzali-Ardakani, U.S. Pat. No. 7,585,431] like polyamic acid is blended, the acidity is low, and an interionic salt is partially formed in the middle of a chain, so that aggregation by microphase separation occurs, and thus, a doping reaction does not effectively occur. Accordingly, the conductivity is low, the processability is deteriorated, and the uniformity of the properties is threatened. U.S. Pat. No. 7,569,271 attempted dispersion in a range of from 0.5 micron to 5 micron since gelation occurs if a size of dispersed particles is overly small, and the dispersed particles are coagulated and flocculated if the size thereof is overly large. Besides, although there have been attempts to modify the ICP itself to improve the properties of the blend, the attempted methods result in decreasing the electrical conductivity, compared to a non-modified ICP, and thus, the utilization of the ICP is restricted. Especially, in order to improve the processability, a method for introducing a structure having a long alkyl group to a conjugate base of a functional organic acid like a dodecylbenzenesulfonic acid, or a method for introducing an alkyl substituent to a benzene ring or a nitrogen atom of a polyaniline main chain has been generally used; however, if a content of the group to be introduced increases, the conductivity is significantly decreased so that the utilization of the ICP is limited to electrostatic prevention or electric gilding.
U.S. Pat. No. 5,232,631 suggested that as the doping method that changes a conjugate ion of a sulfonic acid dopant has received the most attention, the processibility is improved by improving the solubility of the conductive polymer composite in an organic solvent. For example, if a 10-camphorsulfonic acid (CSA), which is a functional organic acid, is used as a dopant of polyaniline, the EB/CSA is dissolved in the organic solvent like meta-cresol so that solution processing is possible. However, there is a problem because the polyaniline having a low molecular weight (intrinsic viscosity of 0.8-1.2 dl/g) is dissolved in 1-methyl-2-pyrrolidone (NMP), and an emeraldine base doped with CSA (EB/CSA) is dissolved in the meta-cresol but gelates when it is kept in a room temperature.